package servlet;

import pojo.User;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

@WebServlet(urlPatterns = {"/user"})
public class UserServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        List<User> users=new ArrayList<>();
        //jdbc操作数据库 查询
        try {
            Class.forName("com.mysql.cj.jdbc.Driver");

            //2.获取连接(url,username,passward)
            String url="jdbc:mysql://127.0.0.1:3306/jdbc?characterEncoding=utf-8";
            Connection connection= DriverManager.getConnection(url,"root","050206yrx");
//           if(connection!=null){
//               System.out.println("连接成功");
//           }
            //3.写sql
            String sql="select * from user";
            //4.预编译sql
            PreparedStatement preparedStatement = connection.prepareStatement(sql);
            //5.有参数设置参数
            //6.执行sql
            ResultSet resultSet = preparedStatement.executeQuery();
            //7.遍历
            while(resultSet.next()){
                User user=new User();
                user.setId(resultSet.getInt(1));
                user.setName(resultSet.getString(2));
                user.setPass(resultSet.getString(3));
                //添加到集合中
                users.add(user);
//                int id = resultSet.getInt(1);
//                String name = resultSet.getString(2);
//                String pass = resultSet.getString(3);
//                System.out.println(id+"------"+name+"-------"+pass+"------");
            }
            //8.关闭资源
            resultSet.close();
            preparedStatement.close();
            connection.close();

            //把集合中数据存储到作用域中
            req.setAttribute("users",users);
            //打开页面
            req.getRequestDispatcher("/user.jsp").forward(req,resp);


        } catch (ClassNotFoundException e) {
            throw new RuntimeException(e);
        }catch (SQLException e){
            throw new RuntimeException(e);
        }

    }
}
